In vitro studies have shown the importance of control of aortic dP/dtmax (dP/dt) as well as arterial pressure in limiting the propagation of aortic dissection. The role of sodium nitroprusside (NP) in the medical management of acute aortic dissection remains controversial. This study assessed the relative efficacy of propranolol (PR) NP, trimethaphan (TR), and combinations of these drugs in treating acute aortic dissection. The importance of various hemodynamic variables in the progression of acute dissection was also examined.